Viscous petroleum recovery process

ABSTRACT

A method for recovering heavy oils and tar sand oils which involves first improving the reservoir permeability without fracturing the reservoir and subsequently flooding the reservoir with hot water or steam. The permeability is improved by establishing some permeability using water injection followed by flooding with an aqueous fluid containing chemical additives which will spontaneously emulsify the oil.

FIP7912 X United States Patent Carlin Dec. 17, 1974 [54] VISCOUS PETROLEUM RECOVERY 3,554,286 1/1971 Feuerbacher at 111 1. 166/272 x PROCESS 3,620,303 I l/l97l Halbert, .lr 166/272 3,637,018 l/l972 Kelly et all l66/272 Inventor: J p C s n, 3,731,741 5/1973 P6111161 et al 166/272 [73] Assignee: Texaco Inc., New York, N.Y.

Primary ExaminerStephen J. Novosad [22] Flled: 1973 Attorney, Agent, or FirmThomas H. Whaley; C. G. 21 Appl. No.: 335,979 Ries 52 us. c1. 166/272, 166/273 [571 ABSTRACT [51] Int. Cl E2lb 43/22 A meth d for recovering heavy oils and'tar sand oils Field of Search which involves first improving the reservoir permeabil- 6 ity without fracturing the reservoir and subsequently flooding the reservoir with hotwater or steam. The References Cited permeability is improved by establishing some perme- UNITED STATES PATENTS ability using water injection followed by flooding with 3,279,538 10/1966 DOSChCl' 166/272 x an aqueous fluid Containing Chemical additives which 3,343,597 9/1967 Gogarty et al 166/273 will Spontaneously emulsify the 3,360,043 12 1967 Braden, Jr. et al. 166/272 3,515,214 671970 Finch 166/272 9 Clams N0 Drawmgs 1 VISCOUS PETROLEUM RECOVERY PROCESS BACKGROUND OF THE INVENTION density approaching or even greater than that of water. The Athabasca tar sands extend for many miles and occur in varying thicknessesof up to more than 200 feet. Although in some places the Athabasca tar sands are disposed practically on the surface of the earth, generally they are located under an overburden which ranges in thickness from a few feet to as much as 100 or more feet in depth. The tar sands located at these depths constitute one of the worlds largest presently known petroleum deposits. In these sands, theoil content ranges between about percent and percent by weight, although sands with lesser or greater amounts of oil content are not unusual. Additionally, the sands generally contain small amounts of water in the range of from about 1 to 5 percent by weight.

The oil present in and recoverable from tarsands is usually a rather viscous material ranging in specific gravity from slightly below 1.00 to about 1.04 or somewhat greater. At a typical reservoir temperature, e.g., about 48F., this oil is immobile, having a viscosity exceeding'several thousand centipoises. At higher tern peratures, such as temperatures about ZOO F. this oil becomes mobile, with viscosities of less than about 343 centipoises. Since this tarry material does not generally command a' very high price, particularly when in its crude state, its separation and recovery must involve a minimum of expenditure in order to beeconomically attractive for commercial practice.

One method of recovering oil from tar sands is to strip mine the sandswith relatively conventional mining apparatus and to process the mined sand to separate oil therefrom. This method has the obvious disadvantage that it is impractical for use in recovering oil from tar sand deposits located at considerable depths below the surface of the'earth. Therefore, the use of strip mining to recover oils from tar sands, such as are located in the Athabasca district of Alberta, Canada, is restricted to those deposits located near the surface of the earth. As a result, only a relatively small percent of the total tar deposits in the Athabasca district'c'an be so'recovered. L

Another method of recovering oil from formations containing viscous petroleummaterials is through the useof thermal-drive techniques which thermally lower the viscosity of oil within the formations and drive the oil so lowered in viscosity to production wells where they may be produced to the surface of the earth through conventional production techniques. Typically', such thermal-drive techniques employ an injection well and aproduction wellextending into the reservoir formation; In operation, a hot fluid, usually steam because of its economic advantages, is introduced into the formation through the injection well. Upon entering the formation, the heat transferred by the hot fluid functions to lower the viscosity of-oil thereinwhile the flow of the hot fluid functions to drive the oil to the production well where it may be produced to the surface of the earth.

It has been found that conventional thermal-drive processes do not generally prove effective in recovering oils from viscous petroleum deposits and tar sands. The reason for this ineffectiveness resides in the fact that the viscous oil will cool and increase in viscosity as it moves away from the well bore where the steam or hot fluid is the most effective. Once the viscous oil attains a high enough viscosity, it banks up and forms an impermeable barrier to further flow toward production wells. In order to overcome this characteristic, it has been proposed to fracture the formation from an injection well to a production well as in US. Pat. No. 3,706,341.

The use of fracturing to facilitate thermal-drive processes has not, however, proved sufficient, in itself, to make thermal-drives in tar sand deposits practical. Such fractures tend to close as soon as the pressure uti lized to create them is relieved. Upon this occurrence, the unheated tar sand reverts to its impermeable state and is not subject to production with conventional ther SUMMARY OF THE INVENTION The invention is a method for recovering heavy oil including tar sand oil from a subterranean reservoir having finite initial permeability without fracturing the reservoir where there is at least one injection well and one production well. The method involves establishing fluid communication between the injection and production wells by injecting an aqueous fluid such as water into the injection well and moving it through the formation toward the production well. After this fluid has begun proceeding toward the production well, a second aqueous fluid is injected into the injection well. This second fluid contains chemical additives capable of forming a spontaneous emulsion with the oil in the reservoir. This second fluid is followed by hot water,

steam or a mixture of the two.

DESCRIPTION OF THE PREFERRED EMBODIMENTS nels between the wells. The formation should not be fractured to force the fluid through the formation. This fluid may be a gas such as methane, carbon dioxide, or nitrogen or a liquid such as brine, produced formation water or water containing emulsion forming additives. It is preferable to use compatible formation water to establish this initial permeability since emulsions may plug the formation if formed before adequate permeability channels have been established. If sufficient initial permeability exists, however, the use of water containing emulsion forming additives is acceptable.

Once this fluid communication is established, a second aqueous fluid is injected through the formation from the injection well to the production well. This fluid is an aqueous solution of a material or materials which will form a spontaneous emulsion with the reservoir oil. As the emulsion is formed and the oil is carried out of the reservoir the preestablished permeability formed during injection of the first fluid become progressively larger, and the permeability increases. This second aqueous fluid must contain materials capable of spontaneously forming emulsions with the oil in the reservoirs. The term spontaneous emulsions and the like refer to emulsions formed in situ upon contact between the aqueous solution and the hydrocarbons or soon after contact.

The materials which in aqueous solution will form emulsions in this way include but are not limited to the following:

1. Alkaline materials including alkali metal hydroxides, alkaline earth metal hydroxides, basic salts of alkali metal hydroxides, basic salts of alkali earth metals and mixtures thereof. Other basic material such as ammonium hydroxide may also be used. Sodium hydroxide is plentiful and is especially preferred for that reason. The pH of the aqueous fluid should be above 7 and preferably between 8 and 13.

2. Alkaline materials as in No. 1 above plus guanidine hydrochloride and fatty soaps, such as sodium oleate are especially preferred. 7

3. Alkaline materials such as in No. 1 above plus guanidine hydrochloride and sulfated fatty alcohol surfactant, such as sodium tridecyl sulfate.

The above enumerated additives to form the second aqueous fluid are given by way of example only and are not intended to be exhaustive. Further, it is within the capability of one skilled in the art to determine the most advantageous emulsion forming system and concentrations in a given case. The above enumerated additives may be used to form aqueous emulsion forming solutions for use as the first injected fluid of an emulsion forming fluid is desirable.

The second aqueous fluid is displaced through the formation from the injection well to the production well to reduce the oil saturation making the relative permerability to aqueous fluids increase. Injection of the second aqueous fluid should most optimally be continued until the ratio of produced aqueous fluid to produced oil becomes uneconomical.

However, once the permeability is sufficient to remove the danger of the banking problem, the second aqueous fluid may cease being injected and the third step of my process, the hot water and/or steam flood, may begin. The steam may be of 100 percent quality or less.

The hot water and/or steam flood may be continued using conventional techniques until the economic limit is reached.

In another typical embodiment of my invention an EXPERIMENTAL The following tests show the effect of displacing various aqueous fluids through sand packs and cores saturated initially with heavy crude oil and/or produced water.

TEST NO. I

A sand pack was evacuated and then saturated with heavy crude oil of 19 API gravity to an initial oil saturation (Sai) of 92 percent. The sand pack was then flooded with produced water to a high water-oil ratio. The residual oil saturation (S inthe pack at the end of the waterflood was 58 percent. The pack was then flooded with produced water containing 0.1 N NaOH and 0.05 percent guanidine oleate until the water-oil ratio began to rise. At this point the S was 35 percent.

TEST NO. II

A sand pack was evacuated and saturated with produced water. The S was 43 percent. The pack was flooded with produced water but no oil was recovered. Following the waterflood the pack was flooded with produced water containing 0.1 N NaOH and 0.05 percent guanidine oleate to a high water-oil ratio. The S was 35 percent at the end of the flood.

TEST NO. III

A linear core was evacuated and fllled with produced water. The water filled core was then flooded to the same crude oil used in previous tests. The S was 84 percent. The core was flooded with produced water to a high water-oil ratio. The S at this point was 59 percent. The core was then flooded with produced water containing 0.1 N NaOH and 0.05 percent guanidine oleate to a high water-oil ratio. The S at the end of this flood was 47 percent.

TEST NO. IV

A linear core was initially saturated with water and oil as in Test No. 3. The S was 81 percent. The core was flooded with produced water containing 0.1 N NaOH and 0.05 percent guanidine oleate to a high water-oil ratio. The S at the end of the flood was 41 percent.

TEST NO. V

A radial core was initially saturated with water and oil as in Test No. 3. The S was 76 percent. The core was flooded with produced water to a high water-oil ratio. The S at this point was 57 percent. The core was there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises:

F LOODlNG RESULTS Water Flood Tertiary Flood S, S,,, Recovery 5,, Recovery Floo 71 7:

No. vlv, 71v, 71v,

l Sand Pack Linear 92.4 57.6 37.7 34.9 62.4 2 Sand Pack Linear 43.3 43.3 0.0 34.3 20.7 3 Core Linear 84.0 59.2 29.7 46.7 44.5 4 Core Linear 8L2 40.8 49.7 5 Core Radial 75.6 57.0 25.3 47.2 37.6

I claim: A. injecting an aqueous fluid through the reservoir 1. A method for recovering heavy oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well. penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises:

A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injection and production wells,

B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide, guanidine hydrochloride and sodium oleate to spontaneously emulsify the oil in the reservoir and I C. injecting steam into the reservoir through the injection well and producing bitumen, steam, and aqueous fluids through the production well.

' 2. A method as in claim 1 wherein the heavy oil is tar sand oil.

3. A method as in claim 1 wherein the steam is less than 100 percent quality.

4. A method for recovering heavy oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises:

A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injection and production wells,

B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide, guani'dine hydrochloride and sodium oleate to spontaneously emulsify the oil in the reservoir and C. injecting hot water.

5. A method as in claim 4 wherein the heavy oil is tar sand oil.

6. A method for recovering heavy oil from a subterranean reservoir without fracturing the reservoir wherein from the injection well to the production well said aqueous fluid containing sodium hydroxide, guanidine hydrochloride and sodium oleate to spontaneously emulsify the oil in the reservoir and B. injecting steam into the reservoir through the injection well and producing bitumen, steam, and aqueous fluid through the production well.

7. A method as in claim 6 wherein the heavy oil is tar sand oil.

8. A method for recovering tar sand oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises:

A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injection and production wells,

B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide and guanidine oleate to spontaneously emulsify the oil in the reservoir and C. injecting steam into the reservoir through the injection well and producing bitumen, steam, and aqueous fluids through the production well.

9. A method for recovering tar sand oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises:

A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injec tion and production wells, 0

B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide and guanidine oleate to spontaneously emulsify the oil in the reservoir and C. injecting hot water. 

1. A METHOD FOR RECOVERING HEAVY OIL FROM A SUBTERRANEAN RESERVOIR HAVING FINITE PERMEABILITY WITHOUT FRACTURING THE RESERVOIR WHEREIN THERE IS AT LEAST ONE INJECTION WELL PENETRATING AND IN COMMUNICATION WITH THE RESERVOIR AND AT LEAST ONE PRODUCTION WELL PENETRATING AND IN COMMUNICATION WITH THE RESERVOIR BY INJECTION OF FLUIDS THROUGH THE RESERVOIR FROM THE INJECTION WELL TO THE PRODUCTION WELL WHICH COMPRISES: A. INJECTING A FIRST AQUEOUS FLUID INTO THE RESERVOIR THROUGH THE INJECTION WELL IN ORDER TO ESTABLISH COMMUNICATION IN THE RESERVOIR BETWEEN THE INJECTION AND PRODUCTION WELLS, B. INJECTING A SECOND AQUEOUS FLUID INTO THE RESERVOIR THROUGH THE INJECTION WELL CONTAINING SODIUM HYDROXIDE, GUANIDINE HYDROCHLORIDE AND SODIUM OLEATE TO SPONTANEOUSLY EMULSIFY THE OIL IN THE RESERVOIR AND C. INJECTING STEAM INTO THE RESERVOIR THROUGH THE INJECTION WELL AND PRODUCING BITUMEN, STEAM, AND AQUEOUS FLUIDS THROUGH THE PRODUCTION WELL.
 2. A method as in claim 1 wherein the heavy oil is tar sand oil.
 3. A method as in claim 1 wherein the steam is less than 100 percent quality.
 4. A method for recovering heavy oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises: A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injection and production wells, B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide, guanidine hydrochloride and sodium oleate to spontaneously emulsify the oil in the reservoir and C. injecting hot water.
 5. A method as in claim 4 wherein the heavy oil is tar sand oil.
 6. A method for recovering heavy oil from a subterranean reservoir without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises: A. injecting an aqueous fluid through the reservoir from the injection well to the production well said aqueous fluid containing sodium hydroxide, guanidine hydrochloride and sodium oleate to spontaneously emulsify the oil in the reservoir and B. injecting steam into the reservoir through the injection well and producing bitumen, steam, and aqueous fluid through the production well.
 7. A method as in claim 6 wherein the heavy oil is tar sand oil.
 8. A method for recovering tar sand oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises: A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injection and production wells, B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide and guanidine oleate to spontaneously emulsify the oil in the reservoir and C. injecting steam into the reservoir through the injection well and producing bitumen, steam, and aqueous fluids through the production well.
 9. A method for recovering tar sand oil from a subterranean reservoir having finite permeability without fracturing the reservoir wherein there is at least one injection well penetrating and in communication with the reservoir and at least one production well penetrating and in communication with the reservoir by injection of fluids through the reservoir from the injection well to the production well which comprises: A. injecting a first aqueous fluid into the reservoir through the injection well in order to establish communication in the reservoir between the injection and production wells, B. injecting a second aqueous fluid into the reservoir through the injection well containing sodium hydroxide and guanidine oleate to spontaneously emulsify the oil in the reservoir and C. injecting hot water. 